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-rw-r--r--lib/math/rational.c16
1 files changed, 11 insertions, 5 deletions
diff --git a/lib/math/rational.c b/lib/math/rational.c
index 9781d521963d..c0ab51d8fbb9 100644
--- a/lib/math/rational.c
+++ b/lib/math/rational.c
@@ -12,6 +12,7 @@
#include <linux/compiler.h>
#include <linux/export.h>
#include <linux/minmax.h>
+#include <linux/limits.h>
/*
* calculate best rational approximation for a given fraction
@@ -78,13 +79,18 @@ void rational_best_approximation(
* found below as 't'.
*/
if ((n2 > max_numerator) || (d2 > max_denominator)) {
- unsigned long t = min((max_numerator - n0) / n1,
- (max_denominator - d0) / d1);
+ unsigned long t = ULONG_MAX;
- /* This tests if the semi-convergent is closer
- * than the previous convergent.
+ if (d1)
+ t = (max_denominator - d0) / d1;
+ if (n1)
+ t = min(t, (max_numerator - n0) / n1);
+
+ /* This tests if the semi-convergent is closer than the previous
+ * convergent. If d1 is zero there is no previous convergent as this
+ * is the 1st iteration, so always choose the semi-convergent.
*/
- if (2u * t > a || (2u * t == a && d0 * dp > d1 * d)) {
+ if (!d1 || 2u * t > a || (2u * t == a && d0 * dp > d1 * d)) {
n1 = n0 + t * n1;
d1 = d0 + t * d1;
}